In digital receivers, received RF signals are converted to extract a digital signal which is supplied to a vocoder portion of the receiver to supply an audio output dependent upon the received input signal. During periods when either a very weak or no RF signal is received there is no audio output from the receiver. This lack of output creates a very poor ambience for the operator, since the operator does not know if the receiver has malfunctioned, no signal is being sent, or there is no audio being sent.
Some manufacturers have attempted to solve this problem by supplying a light on the control panel of the receiver which provides a limited indication of the operation or system acquisition of the receiver. One of the problems with this solution is that the operator must continually watch the control panel. This is not a practical solution, especially when the operator may be doing some other function while operating the receiver.